Fuel usage is still a cost which farmers need to be concerned about for their operations. The September-October 2009 Issue of The Furrow (http://www.deere.com/en_US/ag/online_brochures/furrow_sep_oct2009.html; page 20 “Diesel Down”) has a good reminder article on considerations about how farmers can minimize fuel usage. One piece of the puzzle is the use of Precision Agriculture technologies such as guidance systems and variable-rate technologies which can improve fuel efficiency. Further, I want to point out that modern diesel engines do not need to be idled for extended periods of time like older diesel engines. A 5 to 10 minute cool down or warm up time is sufficient. Bottom-line, with proper planning and attention to machine management, famers can reduce annual fuel costs in an attempt to offset increasing input costs. Further information on methods to save on fuel are outlined in the ACES publication, Fuel Conservation Strategies for the Farm: www.aces.edu/pubs/docs/A/ANR-1303/ and at www.alabamaprecisionagonline.com.

A few days ago, Dr. Fulton asked me to help with the precision-agriculture class. The subject was "guidance systems," and there were three class periods (well, two class periods and one lab period) devoted to the subject. I've always enjoyed being part of this class, especially with this particular subject, for the last few years. A new semester always makes me take stock in just how much the industry has evolved over time---and in such a short time at that! Correction-signal improvements and availabilities, guidance systems and software options that do far more than "stick to the line," sensor-fusion technology, implement guidance---it's a lot to keep up with, that's for sure.

But to be completely honest, more of my fun comes from showing off our autoguidance-equipped tractor to the students. Just "telling" folks what the system can do doesn't hold a candle to letting folks see it for themselves. And, if time allows, we let the students operate the tractor (with close supervision). Now, I'll confess that I enjoy running that tractor as well, because I didn't grow up on a farm. I grew up on what I would call a big family garden; I can't remember the exact model of Ford that my father had at the time---the 1700 looks about right, but this is beside the point. We always have a couple of students that grew up on farms, but most of the students have only seen these big machines from the highway when they drive by. For many, this is their first time ever in such a vehicle, so there's a certain giddiness that I've gotten to see from those students over the years. That's almost worth my sacrifice to sit on that blasted "training seat" ...

Anyway, because of time constraints, I did the driving for the autoguidance demonstrations, but we let the students that wanted to sit in the vehicle with me while I pointed out simple features and drove a preset course. By "preset course," I mean Daniel Mullenix and I put golf balls on tall tees, such that a three-inch-wide paddle mounted to the pull hitch could hit the golf balls---a convincing demonstration to illustrate the accuracy and repeatability of autoguidance. That is, until I decided to drive the course in the opposite direction. I missed every ball that was set up by some four or five inches, easily. This happened every time I drove in the opposite direction from how Daniel and I set up the course; going the right way, no problems. I was wondering at the time how Dr. Fulton was explaining these results to the students, because I sure couldn't offer any good suggestions at the time. RTK is not supposed to behave like that!

When the demonstrations ended, someone came up with the notion of moving the base station (mounted on a survey-style tripod for demonstration purposes) a few inches off kilter to see how the system in the tractor would react to the adjustment. The simple answer: badly. We guessed that the guidance paths were readjusted by the same amount as the base station was moved.

And ... it wasn't until we brought the tractor back to the garage that we noticed the vehicle's receiver was mounted crookedly on the roof. It was slight; a wire had gotten between the dome and the mounting bracket, and this left the receiver tilted to the right by maybe a quarter of an inch. It was just one of those 'oops' things that can happen to anyone. Could that have been enough to explain the wrong-way results we were having with the golf balls? Well, it sure couldn't have helped the situation---apart from the crooked receiver collecting an off-set location, terrain-compensation settings would have been biased. It was a simple fix, but we had to notice it first.

So, what did we learn from all this? I'll give the highlights in the next posting ... in the meantime, for more information, please consult our website: www.alabamaprecisionagonline.com .

In my previous post, I told about our recent in-field experiences with our precision-ag students that were learning about the characteristics and features of guidance systems. I mentioned how our RTK-assisted autoguidance tractor was several inches off of center when we drove a guidance line in the opposite direction, and it left us scratching our heads for a bit. Secondly, I told how we shifted the base station a few inches to the side during an autoguidance operation, and not surprisingly, the guidance paths shifted also. That was kinda fun to see, and it helps to enforce the notion to growers that you better be sure that your base station is mounted securely on a fixed monument, however you choose to do it. Lastly, we noticed later that the receiver on the tractor wasn't seated in the mounting bracket properly, and that certainly could have contributed to the guidance error we witnessed.

With all of that being said, I thought I'd take the opportunity to wrap up this posting by reminding everyone of the following:

If you move your base station around to different fields, periodically check the stability and integrity of your station mount. If you do not use a permanently-affixed mount for your base station, consider doing so for increased position reliability.

Blunders happen, despite our best intentions. Is your antenna dome mounted firmly and properly? When was the last time you actually climbed up on your tractor to look at it up close? Check quality of wires and their connections, from the receiver to the display. If you use a magnetic mount for your RTK-quality receiver, consider creating a more permanent mount for your vehicle.

If you have the opportunity (and can do it safely), let a young, impressionable person ride with you during your operations so that they can experience first-hand what your equipment does. The experience may guide that person to a future in agriculture ... and that'll be good for all of us.

Each year the American Society of Agricultural and Biological Engineers (ASABE) selects a topic for their Distinguished Lecture Series. For 2009, the topic was ‘Automatic Vehicle Guidance’ which was presented by Drs. Arthur Lange and Jorge Heraud both engineers from Trimble Navigation’s Agriculture Division. The title of their presentation was “Agriculture Automatic Vehicle Guidance from Horses to GPS: How We Got Here, and Where We Are Going.” Their presentation was excellent and they both did a great job of covering the history of automatic guidance systems for agriculture. With permission, their presentation and accompanying paper are available for review on the web through the efforts of Dr. Grisso from Virginia Tech’s Biological Systems Engineering Department: http://bsesrv214.bse.vt.edu/Dist_Lecture_2009/.

If you have not reviewed the material, I suggest taking some time to look it over. They present some interesting material highlighting the advances made over the years related to agricultural guidance systems. Thanks to Arthur, Jorge, Dr. Grisso, and ASABE for allowing this material to be easily accessible to everyone. Great work!

The 2009 Precision Ag and Field Crops Conference, set for December 8th at the Wind Creek Hotel in Atmore, Alabama, promises to offer a wide variety of information on precision agriculture (PA) technologies. The conference program will feature sessions on CORS RTK technology, sensor-based variable-rate applications for cotton, and economics of variable-rate applications. Speakers include John Fulton (Auburn University), Randy Taylor (Oklahoma State University) and Terry Griffin (University of Arkansas). The conference will also feature a farmer panel on PA economics, a livestock track on utilizing PA for livestock and forage production, equipment demonstrations and agriculture exhibitors. Detailed information and pre-registration for the conference is available at http://www.aces.edu/anr/precisionag/2009PrecisionAgConference.php

Suppose you return to the field with your guidance equipped tractor to dig peanuts and cannot see your rows for vegetation. You pull up the field record in your guidance system and discover the initial AB line you established weeks ago has shifted two feet! The manufacturer of your equipment advertised sub-foot accuracy for your device…so what happened? GPS drift most likely caused this discrepancy. The accuracy given by the manufacturer is pass-to pass accuracy and is very different from GPS drift.

GPS Drift: Drift can be defined as GPS receiver (guidance system) accuracy over time. Causes of drift are changes in satellite configuration, operating near trees or other obstacles, and satellite data errors (clock errors). The absence of GPS drift would permit each pass to overlay directly onto the established AB lines.

The key to understanding pass-to-pass accuracy versus GPS drift is understanding how changing satellite constellations affect GPS positional accuracy overtime. GPS positional accuracy relies heavily on satellite configuration which is constantly changing as the satellites move across the sky in different orbits. However, it can be assumed that the satellite configuration will not change within a 15 minute period. Relatively the same constellation will be used in providing GPS position data over the 15 minute period and it stands to reason the guidance device positional accuracy will remain fairly consistent within that time frame. On the other hand, satellite configuration is quite different after periods exceeding 15 minutes. If a different satellite configuration is used to determine GPS receiver position, the reported position will almost certainly not correspond to that obtained previously. This “shift” of reported GPS receiver position over time is termed GPS drift.

For more information on GPS, check out our Timely Information at www.alabamaprecisionagonline.com. Stay tuned for future blogs detailing Solutions to GPS Drift.

In my last blog post, Pass-to-Pass Accuracy vs. GPS Drift, we discussed the differences between pass-to pass accuracy and GPS drift and why you may experience drift in farming operations. As the title implies, this blog will focus on finding a solution to drift that is suited to your needs.

First, let me say that matching the type of correction service to your application is important. GPS drift is a function of time and field operations conducted at higher ground speeds or shorter times between adjacent passes (e.g. spraying) can utilize higher drift services without apparent errors. This result occurs because drift accumulation over a short period is small. Other operations (e.g. planting) take place over longer periods or at slower speeds and may lead to unacceptable drift buildup. Thus, RTK correction is recommended for many field operations to improve spatial accuracy over time and minimize drift.

There are two methods used to overcome GPS drift, Shift Track/Nudge feature or GPS correction service upgrade. The Shift Track or Nudge feature allows manual nudging of the AB line to correspond to the crop row and correction service upgrade would entail upgrading to RTK quality.

GPS Drift Solutions:

Shift Track/Nudge feature

GPS Correction Service Upgrade to RTK quality

Required for each in-field operation

May be required multiple times within a specific operation

Requires an absolute reference (e.g. crop row, fence post)

Sub-inch accuracy and repeatability

No user reference required

Free with use of a personal base station

Subscription fee if a modem or privately owned CORS stations are used

Use the table below as a guide when considering guidance device and correction service purchase for your farming needs. For additional information, visit www.alabamaprecisionagonline.com.

With spring fast approaching, now is a good time to ensure you have updated all your equipment to the latest firmware versions. Over the winter months, many technology and equipment manufacturers have posted firmware updates. Some may charge for these updates but others do not. So we suggest you review all your equipment to determine 1) if you can and 2) what it will take to update it. Running current firmware versions allows you to maximize the benefits of the equipment. Here is a list of possible items that may require updates:

GPS receiver

Display or Monitor

Controller

Mobile field software

Desktop software

Please consult your dealer or manufacturer websites to determine whether any updates exists and to address questions. Manufacturers do a good job of posting information about updates online plus provide the necessary steps to successfully complete updates.

Currently, the most accurate means of GPS/GNSS data collection and guidance is with RTK correction. Traditionally, RTK correction required the use of a personal or local base station. While the use of a personal base station on farming operations may be fairly simplistic, in terms of setup, during surveying operations it is particularly cumbersome. In the Biosystems engineering department at Auburn University, we have an RTK base station and several rover units. This base station includes a radio transmitter, several tripods, an antenna, a receiver, and a vehicle battery, all of which must be lugged around for each data collection. Receiving base station data via radio transmitter limits data collection to approximately “line of sight” distance from the base unit. Not to mention, in the event we are not working off of a pre-existing, georeferenced monument, we must leave the base station operating for a minimum of 2 hours to ensure our data is highly accurate.

CORS technology and the ability to receive base station data via the internet has become our saving grace. Through the use of a cellular modem, we have been able to let our personal base station “take a break.” One small modem allows us to stream CORS station data from the internet to our rover unit and has taken the place of almost 80 pounds of bulky equipment. This makes data collection much easier and quicker with the same sub-inch accuracy. We have been using cellular phones as modems for several years, but recently decided to try out a relatively new device; a cellular WiFi node. It is actually smaller than most cellular phones and multiple devices can stream data from it simultaneously. This device is working great.

Key Points:

1. Personal base station data via radio may only reach “line of sight” distances, where as CORS data can be reliable up to 25 miles away. This greatly increases mobility.

1. Keep All Data – Even if you are not planning to use the data during the current growing season it is probable that at some point you will.

2. An Ag GIS software package will enable you to display and work with your data. When selecting a precision ag GIS software package, determine what your current needs are and what your future goals for using precision agriculture are. Make sure the software is compatible with the equipment you are using or may be purchasing. Also consider what user support options are available with your software and whether your program can be upgraded in the future.

3. When purchasing a computer that will be used to manage your precision ag data, make sure the computer’s operating system and memory requirements are compatible for the precision ag software package you choose to use.

4. Develop a file system on your computer that allows you to easily locate your data. This is especially important if there are several individuals who access the data. Use folders and subfolders to group data by years, crops, etc.

5. Frequently back up your data within your software and perform regular backups of your computer. It is a good idea to also store a copy of your data on a CD or other external source and keep the copy in a secure place. There are also several online data storage options available.

With the spring growing season finally underway, many Alabama farmers are fertilizing their fields to enhance crop yields. Most people are familiar with farm-grade fertilizers such as 8-8-8 and 10-10-10. Granular fertilizers are meant to be worked into the ground or sprinkled around plants. It is recommended that they be worked into the ground prior to planting. Granular fertilizers take longer than liquid fertilizers to dissolve into the soil. They can last anywhere from 1 to 9 months, depending on the type. The nutrients need time to break down with some watering, and it usually takes a few days to see results.

Variable-rate technology (VRT) is recommended when applying granular fertilizers. By using VRT, farmers can apply fertilizer and nutrients on a site-specific basis. However, organic fertilizers, such as manure and poultry litter, are commonly used in Alabama. Poultry litter is used extensively in the northern half of the state due to the state’s growing poultry industry. In Alabama, about 2 million tons of poultry litter is generated annually with 90% of it land applied as a fertilizer or soil amendment. Over the years, continuous application of litter has generated environmental concerns due to excessively high phosphorous levels. Therefore, the use of guidance systems, VRT, and other precision agriculture technologies can be used in an attempt to reduce over-application and application in undesired areas.

By forming prescription maps and using VRT during the application process, runoff is reduced and the field is provided with site-specific nutrients. It is also economical! Research has shown that up to 30% of annual costs can be saved. This includes the cost of fuel, labor, and the fertilizer itself. While money is being saved, crop yields are also improved by providing the plants with nutrients as needed throughout the field. By incorporating VRT into the application of granular fertilizers, Alabama farmers can be economical while being good stewards of the land at the same time.

On April 12, 2010, the Federal Aviation Administration (FAA) announced that one of the two WAAS satellites will soon become unusable. The company that manages the satellite, Intelsat, lost control of the Galaxy 15 (PRN 135) satellite used for WAAS service by the FAA. The satellite is expected drift out of its prescribed orbit and the signal will be disrupted for navigational device operators in northwest Alaska. Because there are two WAAS satellites, the rest of the U.S., Canada, and Mexico will be able to function normally with the one remaining satellite. The FAA plans to address this issue in one of two ways. The resolution they are leaning towards is expediting the testing of a new satellite (PRN 133). Testing is already in progress and the satellite was originally expected to be functioning by December 2010. However, due to recent events they now anticipate this satellite will be functional 1 to 2 months sooner than the target date.

This should have little to no bearing on Ag operations using WAAS correction signal in Alabama. However, there is potential for short-term loss of signal (5 minutes) only a few times during this transition period.

Precision agriculture is something that most row-crop producers are familiar with. This is not true with the vast majority of livestock and forage producers. While there are certainly some that have embraced the technology, there are many more that have not done so due to various reasons. Those reasons can usually be boiled down to two big reasons…expense and technology anxiety. Expense is always an issue for livestock and forage producers. Profit margins have always been fairly slim with livestock production. Increasing inputs and stable to decreasing prices over the last couple of years certainly did nothing for improving producer profitability or for increasing producer willingness to embrace new technologies (and the associated costs that came along with those technologies).

However when a producer stops focusing on what the initial input costs are for a guidance system, and looks at the long-term potential benefits associated with the system, the situation becomes much more attractive. Most livestock producers don’t realize the potential over-application associated with spraying or applying fertilizers without some type of guidance assistance. The more progressive producers have tried some form of guidance aid such as foam markers. However when they have the opportunity to use the current precision ag guidance systems, most comment that they far prefer them to foam markers from a standpoint of usability and reliability. It is also worthwhile to note that precision ag technologies, like every other kind of technology, have continued to decrease in price as more products become available on the market. Most producers would probably be money ahead to do a little research into what the current systems cost and what they could potentially save by having the systems.

The other big problem is technology anxiety. Many producers have little to no interest in using technology in general on their operation. Many don’t use email, don’t twitter (or tweet…which is it?), don’t YouTube, etc. There is only one real way to get folks to understand that the technology is not that difficult, and that is to get them to try it. I have heard several producers that tried demo units say that they couldn’t program their VCR, but they could work the GPS system….go figure. If you would like to see some actual livestock producers who tried precision ag systems for the first time (their opinion means a whole lot more than mine does), then go to:

Ever wonder what GNSS, CMR or CORS stands for? Or what a datum or repeater really is? The world of GPS and Precision Agriculture often abounds with confusing terminology and acronyms, especially for those who don’t live there. A new publication is available on the Alabama Precision Ag website defining common GPS/GNSS (see what I mean?) terms, acronyms and components. Check out the new publication GPS/GNSS Related Terminology at http://www.aces.edu/anr/precisionag/GPS.php.

The Precision Ag team has received several phone call this spring about purchasing Guidance Systems and other Precision Ag Technologies such as Variable-Rate Technologies. Typically, a GPS or GNSS receiver is a key component in order to make these technologies function. The term GNSS is relatively new but simply refers to the ability of a GPS/GNSS receiver to utilize multiple satellite-based navigation systems over just the US GPS system. Currently, the Russian GLONASS system is the only other satellite navigation system in operation with the European Galileo and others possibly online in the future. The main benefit of GNSS receivers over GPS-only is the increased number of satellite available for position calculations by the receiver. In return, reliability is increased in areas where GPS-only receivers cannot operate or provide poor accuracy. Further, there exist periods of time during the day that GPS-only satellite counts or availability can be below the required minimum for position calculations due to the operating environment.

Testing here at Auburn University has observed these GNSS benefits especially when operating around tree lines or in rolling terrain. Most GPS and guidance manufacturers offer GNSS solutions which should be considered during purchase. GNSS technology may cost more over GPS-only but can pay off depending upon your operating environment plus provide the most current capabilities.

We recommend considering GNSS receivers when purchasing new Precision Ag technology. They can provide a benefit in agriculture production by increasing reliability through more satellites available under certain operating conditions.

When considering purchasing GPS/GNSS technology for your ag operation, it’s best to do your homework. As with most technology, Precision Ag technology is rapidly evolving and changing to better suit the needs of producers and allow them to become more efficient and better stewards of the environment. The “buzz” words and hot topics of a few years ago may now have been replaced with “later and greater” gadgets. This is the case with GPS/GNSS technology. Recently, new signals have been established such as L2C and L5, which increase reliability of navigation and guidance operations. Likewise, manufacturers of guidance and navigational devices are now producing units capable of utilizing other countries satellite systems in conjunction with GPS. For example, several manufacturers make guidance receivers that are GNSS (Global Navigation Satellite System) capable; meaning they can utilize US GPS satellites as well as others (e.g. Russia’s GLONASS satellite system, etc). This technology holds great advantages in that a GNSS receiver can utilize almost twice the number of satellites a GPS-only receiver is able to use. Additionally, cellular modems can now be used to obtain base station data via CORS (Continuously Operating Reference Stations) or RTN (Real-Time Networks); increasing a producer’s distance from a base station from line-of-sight to over 25 miles when using RTK.

The Alabama Precision Agriculture Team is sponsoring and participating in the International Conference on Precision Agriculture to be held July 18-21, 2010 in Denver Colorado. Team members will present on various topics including Profitability of RTK and Its Influence on Peanut Production, Adoption and Use of Precision Agriculture Technologies and Proper Implementation of Precision Agricultural Technologies for Conducting On-farm Research. In addition the Alabama Precision Agriculture Program will sponsor an exhibit at the conference featuring current projects and outreach efforts of the program. For further information on presentations provided by team members click on the individual titles below. Visit the Alabama Precision Ag Website at www.AlabamaPrecisionAgOnline.com for current precision ag information and updates.

Today’s farm is not our grandparents’ farm that we commonly picture a working farm to be. Old equipment has been replaced with hi-tech machinery that runs in conjunction with GPS to provide accurate planting, fertilizing, spraying, etc. With the technology rapidly advancing, it is not only important to keep up-to-date with improvements and the newest features, but it is also important to network with other farmers that are using precision agriculture technologies.

The emergence of social networking sites such as Facebook, Twitter, and even YouTube now provide opportunities for farmers to stay in touch with each other and the companies that provide precision agriculture technologies and equipment. Farmers now can simply “chat” or “tweet” about problems they might have run into or success stories that might help other farmers. Many equipment and software manufacturers can be found on social networking sites as well. They provide updates on future developments in equipment and useful information for their followers. State cooperative extension systems may also be found on these sites. Auburn University and the Alabama Cooperative Extension System strive to provide Alabama farmers with the most current information about equipment and methods to aid them in their farming practices. Local field days and training events for precision agriculture equipment are announced so farmers can get hands-on experience with the equipment.

One of the best things about social networking is that it is absolutely free! All of this information comes at no cost to the user. Social networking is proving to be a useful tool for the farmers of tomorrow to stay up-to-date with the best practices for growing their crops and managing their farms. Listed below are just some of the many sites and groups utilizing social networking to connect with today’s famers.

While precision ag technologies can provide significant farm savings, correct use and implementation can have a tremendous impact on the level of savings achieved. Reducing off-rate errors and using more efficient operating conditions are important considerations in achieving the maximum benefits of precision technology. Dr. John Fulton, associate professor and Extension specialist at Auburn University, discusses considerations and limitations to think about when utilizing precision technologies in the following podcast from Precision Pays: http://precisionpays.com/2010/08/precision-pays-sometimes-precision-is-not-that-precise/

Read Alabama dairy farmer Will Gilmer's blog post - The Dairyman's Blog- about using GPS technology on their 600-acre farm in Lamar County. Will is participating in the Alabama Precision Ag demo program which allows producers to 'test drive' GPS technology in the field. He points out several advantages to using guidance technology to increase efficiency on the farm, and shows that GPS technology can benefit farms of all kinds and sizes.

Technology today is constantly evolving. It seems that some technical marvel is introduced each day. You can look at the evolution of television screens and see how far they have come in just the past ten years! These technological breakthroughs are not limited to cell phones, televisions, or personal computers. The agriculture industry is adopting cutting-edge technologies to improve farming practices for the end-user, the farmer. Today, several farms have adopted GPS technologies and variable-rate technology (VRT). These systems help producers achieve higher yields while reducing costs of fuel, fertilizers, and other expenses.

Another technology that is currently being researched in the Biosystems Engineering Department at Auburn University is 3D discrete element simulation software for granular agricultural products. The current study is evaluating poultry litter applications by a commercially available spinner-spreader. This spreader is equipped with VRT allowing the change of application rate during the spreading process. Poultry litter particles are created in the software and the geometry of the spreader is uploaded to represent a scenario that is as close to reality as possible. During the simulation process, velocities, forces, and other variables are calculated for the litter particles as they come in contact with other particles and the spreader geometry.

The possible benefits of this simulation software include allowing the equipment manufacturers to study the flow of the material as it makes contact with the conveying and distribution systems. Field tests do not allow for this since the view is constantly obstructed by flying material. Within the simulations, bottlenecks in the delivery process can be addressed by studying the hardware configuration with the goal of achieving a uniform application of poultry litter. In the end, it is hopeful that the time commitment required by equipment manufacturers to design spinner-spreaders is reduced while eliminating the burden on farmers to meet environmental regulations.

The following clip is an example of one of these simulations. Particles can be observed exiting the gate and delivered to the spinning disks by the conveyor. Attributes such as mass distribution, particle count, particle velocities, etc. are measured as the litter is distributed. It is hopeful that simulations such as this prove to be useful in improving the performance of spreader applicators.

Written by Jonathan Hall, Graduate Research Assistant, Biosystems Engineering, Auburn University and Alabama Cooperative Extension System.

With the increasing interest and adoption of precision ag (PA) technologies, “How do I get started in precision agriculture?” is one of the most often asked questions from producers. Consider the following guidelines when adopting PA technology:

1) Have a clear objective in mind with adopting either PA technology and/or practices. Also consider future plans and whether the equipment can be upgraded to perform additional applications or work with additional equipment.

2) Identify the training, support and service tools that are available for your product. Service for your PA equipment is one of the most important things to consider when making your purchase.

3) Buy products that are compatible with multiple operations.

4) Consider whether the technology easy to move between farm equipment and if there will be additional harnesses, cables or equipment needed.

5) Is the technology compatible with your current and/or future equipment?

6) Will you have the ability to record and easily transfer data?

7) Keep all data even if you are not currently utilizing it in your farm management program. Data collected now can often be used in the future.

8) Understand the learning and installation time requirement of PA systems and determine a timeline for implementation.

9) Determine the level of GPS accuracy and repeatability required for your operation. Different levels of GPS correction are more appropriately suited to specific farming practices.

Overall there is no right or wrong approach to PA technology. Choose the technology/equipment that works best for your operation and consider taking it slow and in steps. On-farm studies to evaluate PA practices can be helpful in determining what will provide the best return for your operation. Finally, keep in mind that it can take time to fully start to experience savings or increased profit from precision agriculture. For more detailed information on this topic, see the ACES Timely Information Sheet, Considerations for Adopting and Implementing Precision Agriculture Technologies or visit www.AlabamaPrecisionAgOnline.com.

When trying to learn a new system or perform certain tasks while not having sufficient time to read an entire user’s manual, it’s valuable to have a good source of information to quickly step you through startup and operational procedures. Realizing this need, the Alabama Precision Ag team has developed and assembled some intuitive, step-by-step help guides on various agricultural, surveying and mapping systems. John Deere, Garmin, Trimble, FarmWorks, TeeJet, and Topcon are among the manufacturers of technology and software package help guides featured in this section of the Alabama Precision Ag website. Navigating to this helpful page of Quick Guides is easy, just click here or go to www.alabamaprecisionagonline.com, click Other Resources then Help Guides.

This question is something every farmer must ask themselves before purchasing equipment for implementing precision agriculture practices into their farms. Before this question can be answered, you need to become familiar with the equipment and GPS/GNSS signal options that are available to you. After exploring all of the equipment that can be purchased, you will find that there are three basic options for GPS accuracy:

1. A free signal, known as Wide Area Augmentation System (WAAS), provides pass-to-pass accuracy of about ±6 to 13 inches and has a potential GPS drift of ±4 to ±7 ft. WAAS is managed by the Federal Aviation Administration (FAA).

2. A “corrected” signal that requires a paid subscription can provide a pass-to-pass accuracy between ±2 and ±13 inches and has a potential GPS drift of ±1.7 to ±3 ft depending on the correction service.

3. A real-time kinematic (RTK) system that provides pass-to-pass accuracy of ±1 inch and a potential GPS drift of ±1 inch. This system requires the purchase of an RTK base station if an RTK network, such as CORS, does not already exist in your area. The Continually Operation Reference Station (CORS) network is a free RTK signal operated and monitored by the National Geodetic Survey (NGS). If CORS is not available in your area an annual subscription for a proprietary RTK network can be purchased.

It is important to keep in mind two terms relating to GPS/GNSS accuracy when evaluating signal options. Pass-to-pass accuracy is the accuracy of the GPS/GNSS receiver over a 15 minute time-frame and pertains to short-term operations such as spraying or fertilizing fields. GPS drift is the accuracy of the GPS/GNSS receiver over an extended period of time. GPS drift is more long-term and becomes important when planting or harvesting.

Now that you know what options you have, you can decide which GPS/GNSS accuracy is appropriate for your farming operations. For example, a peanut farmer wants to know where the rows are in his fields when it comes time to harvest. This is difficult due to the foliage of the peanuts running together and obscuring his view of the rows. While harvesting, if he is off by just a few inches, there could be a significant loss in yield. An RTK system would be most appropriate for his farming practices so that he knows exactly where the rows are from the time of planting to the time of harvesting.

Let’s take a look at another example. A cattle farmer wants to plant and fertilize some pastureland for hay. Since he will be using a spreader applicator for broadcasting seeds and applying granular fertilizer, he does not need the same level of accuracy as the peanut farmer. Due to the inherent variability in the application process, it is difficult to achieve high levels of accuracy when broadcasting seeds or fertilizer. GPS drift is not a concern since he will be operating over a short period of time. The use of a “corrected” signal from a paid subscription or WAAS will suffice for the operations of this farmer.

What GPS/GNSS accuracy is needed depends on what operations you need it for. The level of GPS/GNSS accuracy that is needed for your farm can only be determined after evaluating each operation that might take place on your farm. Not every operation needs RTK accuracy. However, if RTK accuracy is needed for one operation, it only makes sense to use it for the other operations that will take place.

The Alabama Precsion Ag team has developed a visual aid to illustrate GPS/GNSS drift. The display is a “to scale” model that allows producers to grasp the impact GPS/GNSS drift can have on an agricultural operation. If you have dropped by the Alabama Precision Ag team’s booth at a conference or field day this year, you have probably had an opportunity to see the display. We have received many inquiries about the display and requests for additional information. There is a new Timely Information sheet on this topic posted on our website, Explanation of GPS/GNSS Drift. Hopefully this blog and Timely Information sheet will answer questions you may have concerning the display or GPS/GNSS drift. If not, please contact a team member for additional information. Below is a description of each part of the display as well as its significance.

Banner: The first paragraph of the banner references a scenario of a producer harvesting peanuts. His tractor is off the target path and the error is attributed to GPS/GNSS drift. Definitions of GPS/GNSS drift and pass-to-pass accuracy allow the spectator to understand why the manufacturer’s advertised accuracy (typically pass-to-pass) may not be experienced in the field. Next, solutions to GPS/GNSS drift are given with upgrading to a lower drift correction (SF 2 or OmniSTAR), or ultimately RTK, recommended. The table illustrated in the banner quantifies pass-to-pass accuracy and drift ranges for four correction services according to Auburn University research. Finally, the last paragraph gives insight into the importance of choosing the appropriate correction service for a particular operation.

Carpet: At the top of the banner, there is a tractor moving across a field. Behind the tractor are four differently colored intervals that come toward the spectator and out of the banner onto the carpet. These colored intervals are “to scale” representations of GPS/GNSS drift or year-to-year accuracy of four correction services. Blue represents WAAS, red represents a sub-meter service, yellow represents a decimeter level service, and green represents RTK level correction. It is evident in figure 1 (left) what a substantialimpact GPS/GNSS drift can potentially have on field utilization efficiency. Note: these cotton rows are planted on 40 inch centers. Standing on this carpet, the spectator can truly appreciate the year-to-year accuracies of these correction services. See figure 2 (below) for a schematic of the full display.

The Alabama Precision Ag team wants to thank everyone who attended our Open House last week. It was great to see such a large crowd interested in our program. We hope everyone learned more about our research and extension focus. Also, thanks to all the companies who have supported our various projects over the past few years. Without your support, we would not be able to deliver beneficial information about precision ag and crop production to farmers and the ag industry across the US. Images from this event can be viewed on our Facebook page: www.facebook.com/AlabamaPrecisionAgOnline. Check them out.

For those who were not able to attend our Open House, you are always welcome to stop by and visit. Just let us know. We would enjoy hosting you.

Everyone on the Alabama Precision Ag team wants to thank those who attended the Wiregrass Cotton Expo last Friday. We enjoyed talking to all of you who stopped by our booth! We want say a special thank you to those who participated in our precision agriculture survey. This will help us better address your interests and needs for the future. For those who were not able to attend, you are welcome to contact us with any questions that you might have about precision agriculture. As always, just let us know if we can help you in any way!

Interest in CORS technology for precision ag applications is quickly expanding in Alabama. This technology enables producers to receive on-the-go RTK corrections from CORS sites through the use of cellular modems or internet-capable cellular phones. Use the link provided on the Alabama Precision Ag website http://www.aces.edu/anr/precisionag/CORS.php to view available and under construction CORS sites for Alabama. It is generally recommended that users operate within a 20 mile radius of the station’s location to receive RTK-level correction.

The interest in guidance systems has been high recently here in Alabama with farmers interested in anything from basic lightbars to more advance RTK autoguidance systems. The options for guidance continues to grow as newer technology and capabilities are integrated into them. One option that farmers should ask about when making a guidance purchase is terrain compensation. Rolling terrain coupled with steep slopes common to several agricultural producing areas of Alabama will impact the performance of guidance systems if terrain compensation is not used to correct GPS/GNSS receiver position data during field operation. Here are some points to consider for those interested in guidance or looking to upgrade:

Terrain compensation is needed when operating on sloped and steep fields.

In general, many lightbar systems do not include a terrain compensation module in the basic package. However, most manufacturers provide it as an add-on component to be purchased separately.

Terrain compensation is included with most RTK autoguidance systems but make sure to check with the guidance manufacturer.

Not all terrain compensation modules correct for the same orientations (e.g. roll, pitch and yaw). Some may only correct for roll while others, all 3. You need to determine what is needed for your field conditions.

Some terrain compensation solutions are integrated into the GPS/GNSS receiver unit while others include a box which must be mounted in the cab of the machine. Just note that different solutions exists between guidance manufacturers.

An extension publication has been posted on our website to address these points along with other information about terrain compensation for guidance systems. It includes purchase considerations along with a list of manufacturers offering terrain compensation.

Sprayer technology has rapidly advanced in recent years with new rate control systems along with technologies such as guidance and automatic section control. While these modern technologies can provide substantial benefits for farmers and/or sprayer operators, they do require proper setup, operation, calibration and maintenance. The primary consideration include selecting the proper nozzles for a specific application, flow meter calibration, and checking nozzle uniformity. These are critical to maximize the benefits of technologies while also maintaining the necessary spray efficacy of products.

During recent on-farm visits, we have found that sprayers are operating outside 10% from the target application rate due to a incorrect flow meter calibration number being set in the controller. This number is something that needs to be routinely checked by the operator especially when changing products. Sprayer and rate control manufacturers have good, detailed calibration procedures to ensure one establishes the correct calibration number. The easiest method to check is to place a known volume in the tank, spray this volume, and then check and see if the controller indicates the same amount of volume has been applied. If the applied amounts are not within a few percent, then the flow meter needs to be re-calibrated. Other procedures exist but consult your operator manual. If you find that this number is inconsistent during your check for a particular product solution, then call your dealer or manufacturer. Incorrect flow meter calibration can lead to unneeded issues!

Another point based on our farm visits, most rate controllers are flow based systems meaning they control flow but not necessarily pressure. This type of control system needs to be well understood by operators since pressure in these flow based systems can vary during field operation (see image). In this example, the pressure ranged from 5 psi to 65 psi during application in 3 fields. We have had the pressure spikes to over 100 psi at times. While this pressure fluctuation may not impact some applications, it can for applications where droplet size is critical for product efficacy (e.g. fungicides). Pressure variations can also impact the risk of drift since these high pressure spikes normally occur when entering and exiting headlands. Again, nozzle selection is important along with sprayer operation to ensure the product is being applied correctly.

These are just a few of many comments about proper sprayer operation. However, here are additional notes and resources to review before heading to the field this season:

Review and follow the calibration procedures by sprayer and technology manufacturers. Don’t base this years setup on last years!

Make sure you are selecting the proper nozzles for the application at hand and expected sprayer operation in the field (e.g. ground speed).

Ensure a pressure sensor is easily visible to the operator so they can keep an eye on it while spraying. This feedback can be important so the operator can maintain the desire pressure range for a nozzle/setup combination.

When we think of Ag GPS/GNSS guidance systems or purchasing a new system, we usually ask ourselves “What is the accuracy of the device?” But how does the guidance device attain that accuracy? And how can you have the same guidance system as your neighbor and get sub-meter accuracy when he is getting sub-inch accuracy?

Generally speaking, and assuming the device has ample satellites in view and no immediate obstructions to block satellites, guidance system accuracy is heavily dependent on two factors, 1) internal processing algorithms and 2) correction service.

The internal processing algorithms (calculations) dictate the intensity at which the receiver will “filter” data to derive a solution. Higher accuracy devices typically filter GPS data m ore rigorously and will discard potentially erroneous data (from multi-path errors, etc.) so that the specified degree of accuracy can be maintained. This contributes to the reason you may be able to go under tree canopy or inside a building with an inexpensive hand-held GPS unit (accuracy of 10 – 15 ft) and get a positional fix then have trouble getting a positional fix even a few yards away from a tree line or a building with an RTK (sub-inch accuracy) GPS/GNSS receiver. Some other contributing factors include: 5 satellites minimum required for RTK, 4 satellites minimum required for WAAS units, ability to process GNSS satellite data and dual frequency receiver capability.

Secondly, correction service is a major factor impacting guidance system accuracy. Different correction services vary widely in provided pass-to-pass and long-term (GPS Drift) accuracies. It is important to note that any one guidance receiver may be capable of operating on several different correction services. However, upgrades, unlock codes, external hardware or subscription fees may be necessary to increase the accuracy of your device. And you should carefully consider your operation when determining which correction service is appropriate for you. A recent Auburn University study (partial study results in figure) illustrates differences in correction service accuracies. All receivers used were placed in a straight line on agricultural equipment and driven through a field with the “reference line” being the path traveled. All receivers used are also capable of operating on different correction services. However, the level of correction service dictated whether the receiver accuracy was 1-inch or over 3 ft.

The Alabama Precision Ag Team is looking for 1 or 2 energetic young people to fill open 2012 summer internships. The internship would include supporting research and extension efforts in the area of precision agriculture. Responsibilities would include assisting with field data collection in support of site-specific agronomic practices under evaluation and technology development. One would be required to setup and troubleshoot machinery and technology being used for field research and demonstrations. The individuals will also help prepare extension material and information and be responsible for downloading field data from machinery plus summarizing it. Interested individuals should be proficient in Word, Excel and PowerPoint and willing to work outside. The experience will provide exposure to new precision ag technologies from various manufacturers and participating in extension activities such as field days.

Please contact Dr. John Fulton for further information if interested: fultojp@aburn.edu.

We know the adoption of precision ag continues to increase across the US. Here in Alabama, technology and site-specific management exceeds national averages reported by the USDA.

In 2009 and 2010, the Alabama Precision Ag Team conducted surveys around the state asking farmers their adoption of many available technologies. Data was collected during winter crop production meetings coordinated by the Alabama Cooperative Extension System (ACES). At that time, adoption in central Alabama was low in comparison to other regions. Therefore, the team has been working to help farmers understand the benefits of technology and how to best implement on their operations in this region. In February of 2013, we were able to repeat the same survey in order to assess how adoption had changed after 3 years collecting data at these same winter meetings.

Results from the 2013 survey and comparison to the 2010 data has been reported in a Timely Information Publication which can be viewed by clickinghere. Of interest, there was a significant increase in Precision Soil Sampling and associated use of Variable-Rate Technology.& Autoguidance and especially RTK increased during this period. A surprise was that yield monitoring jumped from 16% in 2010 up to 48% in 2013. This trend was encouraging as we enter the data management era. Finally, 96% of the farmers have access to high speed internet with 81% requesting more precision ag education.